Cylindrical high-capacity lithium battery pole piece structure and cylindrical high-capacity lithium battery

Abstract

The utility model relates to the technical field of lithium-ion batteries, and discloses a cylindrical high-capacity lithium battery pole piece structure and a cylindrical high-capacity lithium battery. The length of a blank area of ​​a positive pole piece of the cylindrical high-capacity lithium battery pole piece structure, where a positive high-temperature adhesive tape is affixed to the tail, is lengthened to 10 mm, the length of a negative electrode dressing area on the front of a negative pole piece is reduced by 5 mm, and the negative high-temperature adhesive tape overlaps the negative electrode dressing area by 1-2 mm, so that the tail end face of the positive pole piece is easily dropped to the first negative pole blank area affixed with the negative high-temperature adhesive tape during winding, and the problem of cracking of the negative pole piece at the tail end face position of the positive pole piece caused by expansion and contraction of the pole piece after charge and discharge of the cylindrical high-capacity lithium battery is effectively solved.

Description

Technical Field

[0001] The utility model relates to the technical field of lithium ion batteries, in particular to a cylindrical high-capacity lithium battery pole piece structure and a cylindrical high-capacity lithium battery. Background Art

[0002] As an important invention in the 1970s, lithium-ion batteries have quickly become an indispensable energy supply unit in mobile devices such as electric vehicles, smart phones, and tablet computers due to their significant advantages such as high energy density, long life, and low self-discharge rate.

[0003] With the continuous advancement of technology and the continuous expansion of the market, lithium-ion batteries are also facing more and more challenges. Among them, improving energy density is one of the important directions for the development of lithium-ion batteries. Batteries with high energy density can store more energy at the same volume and weight, thereby meeting the needs of electric vehicles and portable electronic devices for long battery life. However, high-energy-density batteries will face a contradictory situation between capacity and assembly ratio in design. In order to solve this problem, researchers began to try to introduce silicon-based negative electrode materials with a higher expansion coefficient.

[0004] However, silicon-based negative electrode materials will produce large volume changes during the charge and discharge process, which may cause damage to the internal structure of the battery and reduce performance. Especially for high-capacity cylindrical batteries, the outermost pole piece will be subjected to greater force during the charge and discharge process, thereby increasing the risk of splitting.

[0005] There are two existing solutions. One is to use expansion tape to allow it to expand freely, reduce the tape's binding effect on the battery cell, and reduce the stress release point's force on the electrode. The other is to reduce the thickness of the positive electrode tail and use blank cutting to reduce the excessive drop at the end face of the positive electrode tail, thereby reducing its force on the negative electrode. However, these two methods are not very effective and cannot ensure that the negative electrode tail is completely unbroken. Utility Model Content

[0006] The utility model provides a cylindrical high-capacity lithium battery pole piece structure and a cylindrical high-capacity lithium battery. The cylindrical high-capacity lithium battery pole piece structure can effectively solve the problem of cracking of the negative pole piece at the tail end surface of the positive pole piece caused by expansion and contraction of the pole piece after the battery undergoes charge and discharge.

[0007] In order to achieve the above-mentioned object, the utility model provides a cylindrical high-capacity lithium battery pole piece structure, including a positive pole piece and a negative pole piece, wherein the positive pole piece includes a positive pole base tape and a positive pole dressing area arranged on the front and back sides of the positive pole base tape, and the negative pole piece includes a negative pole base tape and a negative pole dressing area arranged on the front and back sides of the negative pole base tape;

[0008] A first positive electrode blank area is provided at the tail of the positive electrode base tape, the first positive electrode blank area is 10 mm long, and positive electrode high temperature tape is attached to the front and back sides of the first positive electrode blank area;

[0009] A first negative electrode blank area is provided at the tail of the negative electrode base tape, a negative electrode high temperature tape is attached to the front of the first negative electrode blank area, the negative electrode dressing area on the front of the negative electrode base tape is shortened by 5 mm, and the negative electrode high temperature tape overlaps the negative electrode dressing area by 1-2 mm;

[0010] When the positive electrode sheet and the negative electrode sheet are wound, the tail end surface of the positive electrode sheet faces the first negative electrode blank area to which the negative electrode high temperature tape is attached.

[0011] Preferably, the negative electrode dressing area includes a first negative electrode dressing area arranged on the front side of the negative electrode base tape and a second negative electrode dressing area arranged on the back side of the negative electrode base tape, and the length of the first negative electrode dressing area is greater than the length of the second negative electrode dressing area.

[0012] Preferably, the length of the first negative electrode dressing area is 1005 mm, and the length of the second negative electrode dressing area is 944 mm.

[0013] Preferably, the length of the positive electrode dressing area is 940 mm.

[0014] Preferably, the positive electrode dressing area includes a first positive electrode dressing part and a second positive electrode dressing part, and a blank area with a length of 8 mm is arranged between the first positive electrode dressing part and the second positive electrode dressing part for welding the positive electrode tab.

[0015] Preferably, a first negative electrode ear is arranged on the reverse side of the first negative electrode blank area, a second negative electrode blank area is further arranged at the head of the negative electrode base tape, and a second negative electrode ear is arranged on the front side of the second negative electrode blank area.

[0016] Preferably, when the positive electrode sheet and the negative electrode sheet are wound, the tail end surface of the positive electrode sheet faces the area between the first negative electrode ear and the negative electrode dressing area to which the negative electrode high temperature tape is attached.

[0017] The second aspect of the utility model provides a cylindrical high-capacity lithium battery, wherein the cylindrical high-capacity lithium battery has the above-mentioned cylindrical high-capacity lithium battery pole piece structure.

[0018] Through the above technical solution, the length of the blank area at the tail of the positive electrode sheet where the positive high-temperature tape is affixed is set to 10mm, providing a sufficiently large engineering margin for winding, and the length of the negative electrode dressing area on the front of the negative electrode sheet is reduced by 5mm, so that the tail end face of the positive electrode sheet can easily fall into the first negative electrode blank area affixed with the negative high-temperature tape. At this position, the force exerted by the positive electrode sheet on the negative electrode sheet is small, and the tail end face of the positive electrode sheet faces the tougher negative high-temperature tape, so the negative electrode sheet is not easily cut. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a structural schematic diagram of a cylindrical high-capacity lithium battery pole piece structure provided by the utility model;

[0020] Figure 2 It is a schematic diagram of the structure of the positive electrode sheet in the utility model;

[0021] Figure 3 It is a schematic diagram of the structure of the negative electrode sheet in the utility model.

[0022] Description of Reference Numerals

[0023] 1. Positive electrode base tape; 11. Positive electrode ear; 2. Positive electrode dressing area; 21. First positive electrode dressing part; 22. Second positive electrode dressing part; 3. Positive electrode high temperature tape; 4. Negative electrode base tape; 41. First negative electrode ear; 42. Second negative electrode ear; 5. Negative electrode dressing area; 51. First negative electrode dressing area; 52. Second negative electrode dressing area; 6. Negative electrode high temperature tape; 7. Relative position between the positive electrode tail end face and the negative electrode sheet. DETAILED DESCRIPTION

[0024] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0025] It should be noted that, in the description of the present invention, unless otherwise specified, the terms "front", "back", "head", "tail" and the like indicating the orientation or positional relationship are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0026] In addition, the words "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different parts. The words "include" or "comprise" and similar words mean that the elements before the word include the elements listed after the word, and do not exclude the possibility of including other elements.

[0027] All terms used in the present invention have the same meanings as those understood by ordinary technicians in the field to which the present invention belongs, unless otherwise specifically defined. It should also be understood that terms defined in general dictionaries should be interpreted as having meanings consistent with their meanings in the context of the relevant technology, and should not be interpreted in an idealized or extremely formal sense, unless explicitly defined herein.

[0028] Combination Figure 1 , Figure 2 and Figure 3 As shown, the utility model provides a cylindrical high-capacity lithium battery pole piece structure, including a positive pole piece and a negative pole piece, the positive pole piece includes a positive pole base tape 1 and a positive pole dressing area 2 arranged on the front and back sides of the positive pole base tape 1, the negative pole piece includes a negative pole base tape 4 and a negative pole dressing area 5 arranged on the front and back sides of the negative pole base tape 4, the tail of the positive pole base tape 1 is provided with a first positive pole blank area, the length of the first positive pole blank area is 10mm, and the first positive pole blank area is 10mm long. A positive high-temperature tape 3 is attached to the front and back sides of the white area; a first negative blank area is provided at the tail of the negative base tape 4, a negative high-temperature tape 6 is attached to the front of the first negative blank area, the negative dressing area 5 on the front of the negative base tape 4 is shortened by 5mm and the negative high-temperature tape 6 overlaps with the negative dressing area 5 by 1-2mm; when the positive electrode sheet and the negative electrode sheet are wound, the tail end face of the positive electrode sheet faces the first negative blank area to which the negative high-temperature tape 6 is attached.

[0029] The inventive concept of the utility model solves the problem of cracking of the negative electrode sheet at the tail end surface of the positive electrode sheet caused by expansion and contraction of the electrode sheet after the battery undergoes charge and discharge by setting the structure of the positive electrode sheet and the negative electrode sheet and the positional relationship between the two when winding.

[0030] Specifically, the length of the first positive electrode blank area is increased from the existing 2mm to 10mm, and the positive electrode high temperature tape 3 is attached to the front and back of the first positive electrode blank area to provide a sufficiently large engineering margin for the inevitable fluctuations caused by materials or equipment in the winding process, and the negative electrode dressing area 5 is reduced by 5mm, so that the positive end surface is easy to fall into the empty base tape area, and the negative electrode high temperature tape 6 overlaps with the negative electrode dressing area 5 by 1-2mm to prevent the end surface of the positive electrode sheet from falling on the foil without tape due to fluctuations, thereby avoiding potential battery short circuit risks. In this way, the tail end surface of the positive electrode sheet is easy to fall into the first negative electrode blank area with the negative electrode high temperature tape attached. At this position, the positive electrode sheet has a small force on the negative electrode sheet, and the tail end surface of the positive electrode sheet faces the tougher negative electrode high temperature tape, so the negative electrode sheet is not easy to be cut.

[0031] Specifically, during the winding process, the tail end face of the positive electrode sheet faces the first negative electrode blank area to which the negative electrode high temperature tape is attached. If the negative electrode high temperature tape overlaps the negative electrode dressing area by 1-2mm, then when the end face of the positive electrode sheet falls into the tape area, there will be a 1-2mm safe buffer area to ensure that the tail end face of the positive electrode sheet does not directly contact the foil without tape. This design can avoid the risk of short circuit caused by the tail end face of the positive electrode sheet contacting the foil in case the diaphragm is punctured. It can provide a certain degree of safety protection to ensure that the battery can maintain stable operation in the event of process fluctuations or changes, reduce the risk of battery short circuit, and improve the safety and reliability of the battery.

[0032] In the utility model, the negative electrode dressing area 5 includes a first negative electrode dressing area 51 arranged on the front side of the negative electrode base tape 4 and a second negative electrode dressing area 52 arranged on the back side of the negative electrode base tape 4. The length of the first negative electrode dressing area 51 is greater than that of the second negative electrode dressing area 52. Specifically, the length of the first negative electrode dressing area 51 is 1005 mm, and the length of the second negative electrode dressing area 52 is 944 mm.

[0033] The first negative electrode dressing area 51 is relatively long and can completely wrap the positive electrode material area, ensuring that the lithium ions diffused from the positive electrode have corresponding places in the negative electrode to be accepted and embedded in the lattice, thereby improving the electrochemical performance of the battery. The second negative electrode dressing area is located at the outermost circle of the winding structure and does not correspond to the positive electrode material area. Therefore, no additional negative electrode dressing is required. This design ensures that the positive electrode material area can be wrapped without wasting the negative electrode dressing, thereby effectively optimizing material utilization and reducing production costs.

[0034] In the present invention, the positive electrode dressing area 2 includes a first positive electrode dressing part 21 and a second positive electrode dressing part 22. A blank area of ​​8 mm in length is provided between the first positive electrode dressing part 21 and the second positive electrode dressing part 22 for welding the positive electrode tab 11. By providing a blank area of ​​8 mm in length wider than the tab, sufficient space is provided for welding the positive electrode tab to ensure welding quality and reliability. In addition, under the premise of providing sufficient welding engineering margin and reducing the impact of vibration on the dressing during welding, the blank area for tab welding is made as narrow as possible, saving the use of foil, thereby reducing production costs.

[0035] In the present invention, a first negative electrode ear 41 is arranged on the reverse side of the first negative electrode blank area, a second negative electrode blank area is also arranged on the head of the negative electrode base tape 4, and a second negative electrode ear 42 is arranged on the front side of the second negative electrode blank area. Furthermore, when the positive electrode sheet and the negative electrode sheet are wound, the tail end face of the positive electrode sheet faces the area between the first negative electrode ear 41 and the negative electrode dressing area 5 to which the negative electrode high temperature tape 6 is attached, such as Figure 1 The negative electrode sheet is relatively thin at this position, the positive electrode sheet exerts little force on the negative electrode sheet, and the tail end of the positive electrode sheet faces the high-temperature negative electrode tape 6 with strong toughness, so the negative electrode sheet is not easily cut.

[0036] The second aspect of the utility model provides a cylindrical high-capacity lithium battery, which has the above-mentioned cylindrical high-capacity lithium battery pole piece structure.

[0037] It can be understood that the cylindrical high-capacity lithium battery with the above-mentioned cylindrical high-capacity lithium battery electrode structure can effectively avoid the problem of easy cracking of the negative electrode at the tail end of the positive electrode after charging and discharging, thereby ensuring the safety, reliability and performance consistency of the battery during use.

[0038] The cylindrical high-capacity lithium battery pole piece structure provided by the utility model is further described below through specific embodiments.

[0039] Embodiment 1

[0040] The present embodiment provides a method for manufacturing a cylindrical high-capacity lithium battery pole piece structure, comprising the following steps:

[0041] 1. Prepare 20 groups of positive electrode sheets, the coating length of the front and back sides of each group of positive electrode sheets is 627mm+313mm=940mm, the length of the blank area on the front and back sides of the tail of the positive electrode sheet is 10mm, the blank area on the front and back sides of the positive electrode sheet ear welding part is 8mm, and the blank areas on the front and back sides of each group of positive electrode sheets are attached with positive high temperature tapes, and the width of the positive electrode sheet is 63mm;

[0042] 2. Prepare 20 groups of negative electrode sheets, the front coating length of each group of negative electrode sheets is 1005 mm, the back coating length of each group of negative electrode sheets is 944 mm, and the front blank area at the tail of each group of negative electrode sheets is pasted with a negative electrode high temperature tape with a width of 17 mm. The negative electrode high temperature tape overlaps the negative electrode dressing area by 2 mm, and the width of the negative electrode sheet is 64.5 mm;

[0043] 3. When each group of the positive electrode sheet and the negative electrode sheet is wound, the tail end surface of the positive electrode sheet falls on the glue sticking position between the tail ear of the negative electrode sheet and the coating.

[0044] Comparative Example 1

[0045] This comparative example provides a method for manufacturing a cylindrical high-capacity lithium battery pole piece structure in the prior art, comprising the following steps:

[0046] 1. Prepare 20 groups of positive electrode sheets, the coating length of the front and back sides of each group of positive electrode sheets is 627mm+313mm=940mm, the length of the blank area on the front and back sides of the tail of the positive electrode sheet is 2mm, the blank area on the front and back sides of the positive electrode sheet ear welding part is 8mm, and the blank areas on the front and back sides of each group of positive electrode sheets are attached with positive high temperature tapes, and the width of the positive electrode sheet is 63mm;

[0047] 2. Prepare 20 groups of negative electrode sheets, the front coating length of each group of negative electrode sheets is 1010 mm, the back coating length of each group of negative electrode sheets is 944 mm, the negative electrode high temperature tape is applied to the welding area of ​​the tabs of each group of negative electrode sheets, and the width of the negative electrode sheets is 64.5 mm;

[0048] 3. When each group of the positive electrode sheet and the negative electrode sheet is wound, the tail end surface of the positive electrode sheet falls on the tail coating area of ​​the negative electrode sheet.

[0049] The test group samples and the comparison group samples obtained by performing the pole piece design according to Example 1 and Comparative Example 1 were set aside for 15 days after the capacity was divided and then disassembled. The disassembly results are summarized in Table 1:

[0050]

[0051] As shown in Table 1, the defective number refers to the number of samples with cracked negative electrode sheets after each group of samples was disassembled. It can be seen from the results in Table 1 that, compared with the prior art, the utility model can effectively solve the problem of cracking of the negative electrode sheet at the tail end surface of the positive electrode sheet caused by the expansion and contraction of the electrode sheet after the battery undergoes charging and discharging, thereby ensuring the safety, reliability and performance consistency of the battery during use. The utility model reduces the negative electrode dressing and reduces the battery BOM cost.

[0052] The preferred implementation modes of the present invention are described in detail above in combination with the accompanying drawings and embodiments, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations. However, these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A cylindrical high-capacity lithium battery pole piece structure, comprising a positive pole piece and a negative pole piece, wherein the positive pole piece comprises a positive pole base tape (1) and a positive pole dressing area (2) arranged on the front and back sides of the positive pole base tape (1), and the negative pole piece comprises a negative pole base tape (4) and a negative pole dressing area (5) arranged on the front and back sides of the negative pole base tape (4), characterized in that: A first positive electrode blank area is provided at the tail of the positive electrode base tape (1), the first positive electrode blank area has a length of 10 mm, and positive electrode high temperature adhesive tapes (3) are attached to the front and back sides of the first positive electrode blank area; A first negative electrode blank area is provided at the tail of the negative electrode base tape (4), a negative electrode high temperature adhesive tape (6) is attached to the front of the first negative electrode blank area, the negative electrode dressing area (5) on the front of the negative electrode base tape (4) is shortened by 5 mm, and the negative electrode high temperature adhesive tape (6) overlaps with the negative electrode dressing area (5) by 1-2 mm; When the positive electrode sheet and the negative electrode sheet are wound, the tail end surface of the positive electrode sheet faces the first negative electrode blank area to which the negative electrode high temperature adhesive tape (6) is attached.

2. The cylindrical high-capacity lithium battery pole piece structure according to claim 1, characterized in that: The negative electrode dressing area (5) comprises a first negative electrode dressing area (51) arranged on the front side of the negative electrode base tape (4) and a second negative electrode dressing area (52) arranged on the back side of the negative electrode base tape (4), wherein the length of the first negative electrode dressing area (51) is greater than the length of the second negative electrode dressing area (52).

3. The cylindrical high-capacity lithium battery pole piece structure according to claim 2, characterized in that: The length of the first negative electrode dressing area (51) is 1005 mm, and the length of the second negative electrode dressing area (52) is 944 mm.

4. The cylindrical high-capacity lithium battery pole piece structure according to claim 3, characterized in that: The length of the positive electrode dressing area (2) is 940 mm.

5. The cylindrical high-capacity lithium battery pole piece structure according to claim 1, characterized in that: The positive electrode dressing area (2) comprises a first positive electrode dressing part (21) and a second positive electrode dressing part (22), and a blank area with a length of 8 mm is provided between the first positive electrode dressing part (21) and the second positive electrode dressing part (22) for welding the positive electrode tab (11).

6. The cylindrical high-capacity lithium battery pole piece structure according to claim 1, characterized in that: A first negative electrode ear (41) is arranged on the reverse side of the first negative electrode blank area, a second negative electrode blank area is also arranged at the head of the negative electrode base band (4), and a second negative electrode ear (42) is arranged on the front side of the second negative electrode blank area.

7. The cylindrical high-capacity lithium battery pole piece structure according to claim 6, characterized in that: When the positive electrode sheet and the negative electrode sheet are wound, the tail end face of the positive electrode sheet faces the area between the first negative electrode ear (41) and the negative electrode dressing area (5) to which the negative electrode high temperature tape (6) is attached.

8. A cylindrical high-capacity lithium battery, characterized in that: The cylindrical high-capacity lithium battery has the cylindrical high-capacity lithium battery pole piece structure as described in any one of claims 1-7.

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